Method of producing suede finish



Patented June 11, 1940 UNITED STATES,

PATENT OFFlCE .mn'rnop or rno ponvo SUEDE FINISH Ernest Rudolf Stermforest Hills, N. Y., assignor to Sande: Chemical Works, Inc., New York. N. Y.,acorporation of New York Serial No. 184,249

No Drawing. Application January 10, 1938,

such a method and procedure required considerable time, in addition to being very tedious and uneconomical.

The instant invention overcomes the disadvantages of the prior art and provides an economical method of producing a non-crocking suede finish preferably having a luster or sheen and silky feel or hand comparable to genuin French antelope.

The instant invention further contemplates producing a non-crockingsuede finish, preferpreferably more,'can be simultaneously treated at one time.

The instant invention further provides a. method wherein the steps of appropriately coloring the skins and rendering the fibers thereof in condition for the development of the desired sheen and feel are performedin an apparatus. in a relatively short period of time whereby th tedious manual operations are overcome. Other objects 01' the invention will become clear and apparent from the following description and appended claims.

As is clear from the objects-one of the essential features of the invention contemplates the production of a non-crocking suede finish preferably having a luster or sheen and silky hand or feel comparable to genuine Frenchantelope.

The suede finish contemplated by the instant invention may be provided onto tanned stock (leather) produced from kid, calf,- sheep suede, splits or the like, irrespective of the tannage. 'Thus, the leather which is to. be provided with the desired suede finish may betanned with of the known tannage's, .such as,' for example, chrome tannage, aldehyde tannage, vegetable tannage, iron tannage, or any skin in which the gelatin thereof has been converted to a tanned condition. Whenthe ta'nnage is other than chrome tannage, the former is stripped and a chrome tannage substituted in whole orpart therefor. 3

In accordance with the principles of the method constituting one phase of the instantinvention, the selected stock which is to beprovided with a suede finish having a luster or sheen and silky feel or hand comparable to genuine French antelope is provided with a body or foundation color depending on the color desired in the final product. After the stock has been colored, it is treated to render at least the surface fibers thereof in condition so that, upon finishing, as hereafter more fully described, the luster or sheen and silky feel or hand are obtained.

Prior to or simultaneously with the treatment of the stock in order to render the surface fibers thereof in condition for producing the sheen and feel by finishing, the stock may be further dyed so as to produce the desiredtinctorial effect (tone control) in the final product.-

' All of the aforementioned steps, except the finishing, are performed at controlled temperature conditions in an apparatus. In other words,

the coloring of the stock to the desired tone and the chemical treatment of the surface fibers are effected in an apparatus under controlled temperature conditions.

In thepreferred-embodirnent of the invention =the previously mentioned steps of producing the desired tinctorial effects and converting the fibers so that the desired luster or sheen and silky feel or hand are secured upon finishing are effected in a drum under controlled temperature conditions. The drum is of any shape and of such dimensions or capacity so that the relatively large number of skins (fifteen dozen or more) which are to be treated at one working and the reagents added during the process fill only a portion of the drum, such as one-third thereof. The drum is provided with an appropriate temperature control device whereby the temperature of the contents thereof maybe regulated or controlled during the process.

When the skins are given a beating action during-the various stages of the process, better results are secured. .The beating action of the skins may be secured in various manners. In one formof the invention this can be secured by providing the skins and the reagents employed in the various stages of the process with a relative movement with respect to each other. This can be secured by imparting a rotary, tumbling or combined rotary-tumbling, or any other movement of the drum which imparts relative movement between the materials constituting the contents thereof during the process. When an increased beating action is desired, this can be secured by providing rubber balls inithe drum. Thus; upon rotating or tumbling of .the drum, the balls will also aid in beating the skins. 'Another form of increasing the beating action can be secured by providing the interior surfaces of the drum'with means, such as, for example, pegs. or-narrow'shelves, disposed at spaced intervals. In this construction, upon rotation or tumbling of the drum, the goods are alternately removed from the solution and then dropped into the solution, whereby an added beating effect'is secured. If desired, both of the aforementioned means for enhancing the beating action may be employed simultaneously.

The drum is also provided with means whereby the-various solutions employed in the process may be introduced therein and also with means for removing the solutions during the process as it becomes necessary so to do.

In the preferred embodiment of the invention, the drum is mounted on hollow trunnions through at least one of which the various treating agents are introduced as desired, even while the drum is in motion. The outlet is provided at any appropriate place on the drum. The drum is furthermore provided with a door or the like through! which the skins to be. processed are introduced and the processed skins removed after treatment.

In carrying out the process, not less than fifteen dozen skins tanned with chrome tannage,

as hereinbefore described, are introduced into the drum and the drum is given a movement of the .type hereinbefore described.

Usually, tanned skins have a crust condition and contain foreign substances. When this con dition is present in the stock it becomes necessary to prepare the stock so as to make it amenable to the treatments which it is to undergo in the process. With this in view, the stock is wet back from the crust condition thereof. As a consequence, the foreign substances are removed from the stock and the latter is so thoroughly wetted that it is in a softened open condition. The! wet back treatment depends on the condition of the stock. Satisfactory results are secured when the stock is wet back for approximately 30 minutes in plain water at approximately -160" F.

After the stock has been wet back as previously described, the liquor is dropped and there is introduced into the drum a composition which incorporates an oil into the stock whereby the fibers thereof are softened. Due to the nature of the composition, any possibility of grease on the surface of the product is eliminated. In the preferred embodiment of 'this invention, this composition is an aqueous emulsion of a mineral oil. The mineral oil is preferably a white stainless mineral oil which has a viscosity of 60 to at 20 F. when tested in a Saybolt viscosimeter. Any suitable emulsifying agent may be used. Triethanolamine, Twitchells oil base (mixture of sulphonated olefinic compounds), sulphonated oils, fats, etcare several illustrative emulsifying agents which may be employed. One emulsifying agent or a plurality thereof may be used.

The proportions of the ingredients constituting the emulsion are such as to produce an emulsion having a relatively fine or small particle size. A specific illustrative emulsion which has given satisfactory results-consists of 70 parts of mineral oil and 30 parts of Twitchells oil base (the proportions being by weight) and a suilicient amount of water to give the desired fine particle size. In producing this emulsion, the mineral oil and the emulsifying agents are mixed together and the mixture agitated or stirred until a substantially uniform and homogeneous mixture is obtained. While the agitation is continued, a sufiicient quantity of water is added to produce the desired particle size and viscosity. A sufficient quantity of the resulting emulsion is applied to the wet back stock. Though various quantities of emulsion may be introduced into the drum, satisfactory results are secured when an amount of emulsion containing 0.25% to 10% by weight of oil based on the dry weight of the tanned skins is used. The stock is drummed with the emulsion for a sufficient period of time and at a temperature of 13. to F. to permit said emulsion to penetrate into the stock. In practice, the desired results have been secured when the wet back stock is drummed with the emulsion for approximately 30 minutes.

After drumming the stock with the emulsion as immediately before described, the liquor is dropped and the stock is in condition and ready to receive its body or foundation color which is produced through the medium of dyestuffs. The dyestuffs employed for producing the body or foundation color depend on the tinctorial or tone value desired in the final product. Thus, when a dark color is desired, the dyestuff employed in the production of the body or foundation color is one which will produce a dark shade. Likewise, when a light tone effect is desired, a dyestufi which produces a light color is employed in the coloring of the body or foundation color. Though various dyestuifs may be used for producing the foundation color, I prefer those dyestuffs herein referred to as Derma dyestuffs. As illustrative examples of Derma dyestuffs for producing several illustrative colors may be mentioned the following dyestuifs manufactured and sold by the Sandoz Chemical Works of New York:

y Color Dermacarbon B Cone Black. Derma blue 2B Cone. Blue. Derma brown G Conc Brown Derma brown R Conc Do.

In some instances in order to produce the desired tone of the body or foundation, a mixture of two or more dyestufis may be used. For example, when a deep black is desired, Dermacarbon B Cone. may be mixed with an appropriate quantity of some other aniline dyestuif, such as, for example, Chloramine Dark Green B Cone, color index #583, or some other green color. The relative proportions of the two dyestuffs depend, of course, on the desired tone to be produced.

Though the body or foundation color may be introduced by a single dye application, a better.

more level and deeper color is secured when the dyestuff is applied in several applications. Hence, the invention contemplates a plurality or several applications of the dyestufi for producing the body or foundation color. I

When the dyestuff or dyestuffs employed in the production of the body or foundation color are of the type which requires a mordant, a suitable mordant is incorporated at the same time that the foundation dyestuif or dyestuffs are applied. When the foundation color is produced by several applications of dyestuffs, sufficient mordant is applied in the first stage so as to make it unnecessary to apply it in the second or subsequent applications.

Any suitable mordant which does not affect the fibers of the stock but acts only on the dyestuif may be employed.- Oxidizable chromium salts have been found especially suitable for this purpose. More satisfactory results are secured when, inconjunction with the oxidizable chromium salts, there is also used a polybasic acid (aliphatic or aromatic), preferably a dicarboxylic acid. As a specific illustrative example of a suitable oxidizable chromium salt may be mentioned sodium bichromate, and as a suitable polybasic acid may be mentioned oxalic, citric, etc. If desired, the chromium salt and the polybasic acid may be mixed together prior to the incorporation in the dye bath. Alternatively, the ingredients constituting the mordant may be added separately to the bath. Thus, the stock may be first stricken with bichromate and then with the selected polybasic acid. The quantity of mordant which may be used depends, of

and the dyestuif is a mixture consisting of 0.5% to 20% Dermacarbon B. Cone. and 0.0625% to 5% Chloramine Dark Green B. Conc. and is drummed at 140 to 160 F. for 45 minutes, and the second application consists of a mixture of 0.25% to 10% Dermacarbon B Cone. and 0.0625% to 5% Chloramine Dark Green B Cone. and is drummed for 30 minutes at 140 to 160 F.

In order to exhaust the dye and to drive the color on to the stock, there is added to the dye bath, preferably in stages, a weakly ionized or ganic acid, such as, for example, an organic acid which has a dissociation constant not over 10- Though formic acid is preferred, other acids having the dissociation constant mentioned, such as, for example, citric, acetic, tartaric, Zactic, boric, maleic, may be used. Best results are secured when the acid is added at predetermined intervals in each dye application.

. Thus, when the dye application is in two stages, as immediately before described, after the first dye application has been drummed as described, there is added at 10 minute intervals a total of 3 feedings, each containing 0.5% to 20% of formic acid at F. and, after the second dye applica tion and drumming, there is added at 10 minute intervals a total of 3 feedings, each containing 0.25% to 20% formic acid at 135 F. Thereafter the liquor is dropped. The quantity of acid employed is greater than that necessary to exhaust the dyestuffs from the baths and the reason for this will become apparent from the description hereinafter.

After the stock has been given the desired body rendered in condition so that, upon finishing in accordance with the type of suede desired,. the desired properties, such as luster or sheen and silky feel or hand, are secured. This condition of the fibers is secured through a deterioration of the fibers which, in the preferred form of the invention, is secured by a chemical reaction between the reagents upori the surface of and within the fibers and an appropriate reagent or re agents. Prior toor simultaneously with the deterioration of the fibers, the latter are treated so as to either split the tops of the fibers or spread apart the fibers in the fiber bundles, or both. This step is herein referredto as the fiber separation.

The fiber separation is effected by means of iron hydroxide which is produced in situ in at least the top portions of the surface fibers. According to the invention, there is produced an iron tannate on the surface fibers-and a small part of this 'iron t'annate is converted into the hydroxide. Due to the excess acid employed in the dye exhaustion step, there is produced an acid environment on and in the skins, whereby the, precipitation of the irontannates is retarded.

In practice, after the stock has been colored and the dye liquor dropped, there is introduced into the drum 1% to 20% of tannic acid-bearing materials, such as hematine crystals, fustic crystals, stainless sumac extract, dyewoods, vegetable tanning matter, and the contents maintained at F. Due to the acid condition of the stock resulting from the excess acid employed in the dye exhausting steps, the tannic acid-bearing materials are kept on the surface of the stock, A suitable quantity, such as 0.25%-

to 20%, of iron (preferably ferrous) salts is then added, whereby an iron tannate is produced.

As previously explained, the acid environment retards oxidation of the iron salts, thereby retarding the precipitation of the iron tannates. After being drummed for 15 minutes, the liquor is dropped and the temperature raised to 135 F. and there is added 0.5% to 10% of an alkali or alkaline salt, such as borax, soda, etc. The alkali neutralizes the acid to the point where iron hydroxide. is nearly precipitated.

After the addition of the alkali, the materials are drummed for 15 minutes andafter dropping the liquor, 0,0625% to 20% of a mildly, basic aromatic amine, such as paraphenylene diamine, meta toluylene diamine, etc., is added and drumming continued for one hour, after which the stock is removed fromv the drum, horsed up for oxidation and dried in a cool room. The skins are then finished as hereafter described to produce the luster or sheen and silky feel or hand.

When the amine is added, a reaction sets in which deteriorates parts of the line surface fibers.

The alkali has produced such a parses the mild alkalinity of the aminedecomposes some of the iron tannate to produce a bulky-precipitate of iron hydroxide. 'Ihe bullw iron hydroxide sepaamine remains on the surface of the fiber topermit oxidation by the air, whereby further deterioration is secured. The deterioration converts the fibers into the desired condition.

In the event the color of the stock is not the exact tone desired, prior to the application of the amine a suflicient quantity of a dyestuff, such as a basic aniline dyestuif-in an amount of 1% to 10%, is added to bring the color to the desired tone. When this step is employed, the materials are drummed 30 minutes, the liquor dropped and the amine added as described.

The skins are then finished in accordance with the type of suede finish desired. When a noncrocking suede finish is desired, the skins are finished by drying and dry milling in the manner used in making ordinary suede. When a noncrocking suede'finish having a luster and silky feel is desired, the skins are finished as hereafter set forth.

After the skins have been dried inthe cool room, they are taken down and put into wet saw dust in which-they are left, according to'the type of skins, from 4 to 12 hours. The skins are then taken out of the saw-dust and staked and, after they have been staked once, they-are blocked with an emery block.

If sheep skins constitute the basis of the stock,

plushed, ironed, staked, and plushed again.

In order to more fully explain theinvention, there is hereafter set forth an illustrative example for producing a deep black product. The proportions are by weight based on the dry weight of the tanned skins in crusted condition.

The desired number of tanned skins of the selected stock is introduced into the drum and wet back for 30 minutes in plain water at 160 F. After dropping the liquor, there is added a sufficient quantity of the mineral oil emulsion so as to provide 3% of the mineral oil. After drumming for 30 minutes, the liquor is dropped and there is added a previouslyprepared mixture containing 4 of Dermacarbon Black B Gone. and 0.75% of Chloramine Dark Green BConc. Either simultaneously with or subsequently to the introduction of the dyestuffs; there is added 3% of the bichromate polybasic acid mordant. After drumming for 45 minutes at 160 F., there is added in three feedings at 10 minute intervals at 135 F. 1.25% of formic acid for each feeding. Then there is added a mixture containing 4% of Dermacarbon Black B Cone. and 0.75% of Chloramine Dark Green B Conc. After drumming for 30 minutes of 160 F., there is added in three feedings at 10 minute intervals 1.25% of formic acid for each feeding. The liquor is then dropped and a mixture of 5% of hematine crystals, 1.50% of fustic crystals and 1.50% of stainless sumac extract at 145 F. is added and the mass drummed for 30 minutes at 145 F. The.

mass is then stricken with 5% of copperas and 1% of iron nitrate (ferric sulphate, ferric sulphate nitrate, basic ferric sulphate nitrate) and drummed for minutes, after which the liquor is dropped. The temperature is brought back to 135 F. and 2% of borax is added. After drumming for 15 minutes, there is added 4% of basic aniline dyestuffs. After drumming for minutes, the liquor is dropped and 1% of paraphenylene diamine is added. After drumming for 1 hour, the skins are removed from the drum, horsed up for oxidation. and dried in a-cool room. The skins are then finished as previously described.

The product resulting from the specific procedure hereinbefore set forth is a deep black soft leather having a non-crocking suede finish characterized by a luster or sheen and silky feel or hand comparable to genuine French antelope. Obviously, by using appropriate dyestuffs, other colored products can be produced. By utilizing the finishing procedure normally used in the production of regular suede and varying the times and concentrations of the specific procedure hereinbefore set forth, as will be obvious to a person 1. In a method of producing a colored suede finish on skins containing chrome tannagathe steps which comprise dyeing a plurality of the selected skins, separating the fibers by chemically producing a bulky deposit on and between the fibers on the'surface of the dyed skins, and subjecting the skins to a finishing treatment.

2. In a method of producing a colored suede finish on skins containingchrome tannage, the

steps which comprise dyeing a plurality of the selected skins, forming iron hydroxide in and on at least the top portions of the fibers onthe surface of the dyed skins, by causing an iron compound in the presence of alkaline compounds to react with an aromatic amine, and subjecting the skins to a finishing treatment.

3. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise dyeing a plurality of the selected skins, forming an iron compound in and on at least the top portions of the fibers on the surface of the dyed skins, again dyeing the skins to produce the tinctorial effect desired in the final product, causing said iron compound in the presence of alkaline compounds to react with an arcmatic amine, and subjecting the skins to a finishing treatment.

4. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise treating a plurality of wet back skins with an aqueous mineral oil emulsion, dyeing said skins, separating the fibers by chemically producing a bulky deposit on and between the fibers on the surface of the dyed skins, and subjecting the skins to a finishing treatment.

5. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise treating a plurality of wet back skins with an aqueous mineral oil emulsion, dyeing said skins, forming iron hydroxide in and on at least the top portions of the fibers on the surface of the dyed skins by causing an iron compound in the presence of alkaline compounds to react with an aromatic amine, and subjecting the skins to a finishing treatment.

6. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise treating a plurality of wet back skins with an aqueous mineral oil emulsion, dyeing said skins, forming an iron compound in and on at least the top portions of the fibers on the surface of the dyed skins, again dyeing the skins to produce the tinctorial effect desired in the final product, causing said iron compound in the presence of alkaline compounds to react with an aromatic amine, and subjecting the skins to a finishing treatment.

7. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise dyeing a plurality of the selected skins in the presence of an amount of a weakly ionized organic acid in excess of that required to exhaust the dye whereby an acid environment is produced in the skins, forming iron tannate in and on at least the top portions of the surface fibers, neutralizing the acid with an alkaline compound to a point where a portion of the iron tannate is nearly precipitated as iron hydroxide, applying an aromatic amine in an amount in excess of that required to precipitate the iron hydroxide, permitting the excess amine to oxidize, and subjecting the skins to a finishing treatment.

8. In a method of producing a colored suede finish on skins containing chrome tannage, the 7 steps which comprise dyeing a plurality of the selected skins containing chrome tannage in the presence of an amount of an organic acid having .a dissociation constant not over 10-- in excess of that required to exhaust the dye whereby an acid environment is produced in the skins, formas iron hydroxide, applying an aromatic amine in an amount in excess of that required to precipitate the iron hydroxide, permitting the excess'amine to oxidize, and subjecting the skins to a finishing treatment.

9. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise dyeing a plurality of the selected skins containing chrome tannage in the presence of an amount of an organic acid having a dissociation constant not over 10- in excess of that required to exhaust the dye whereby an acid environment is produced in the skins, forming iron tannate in and on at least the top portions of the surface fibers, neutralizing the acid with an alkaline compound to a point where a portion of the iron tannate is nearly precipitated as iron hydroxide, again dyeing the skins to produce the tinctorial efiect desired in the product, applying an aromatic amine in an amount in excess of that required to precipitate the iron hydroxide, permitting the excess amine to oxidize, and subjecting the skins to a finishing treatment.

10. In a method of producing a'colored suede finish on skins containing chrome tannage, the steps which comprise treating a plurality of wet back skins containing chrome tannage with an aqueous mineral oil emulsion, dyeing the skins in the presence of an amount of a weakly ionized organic acid in excess of that required to exhaust the dye whereby an acid environment is produced in the skins, treating the dyed skins with a composition containing tannic acid-bearing materials, striking the skins with an iron salt, neutralizing the acid to a point where some iron hydroxide is nearly precipitated, adding an aromatic amine in an amount in excess of that required to precipitate the iron hydroxide, permitting the excess amine to oxidize, drying the skins, and finally subjecting the skins to a finishing treatment.

11. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise treating a plurality of Wet back skins containing chrome tannage with an aqueous mineral oil emulsion, dyeing the skins in a dye bath containing an organic acid having a dissociation constant not over 10- and in an amount in excess of that required to exhaust the dye whereby an acid environment is produced in the-skins, treating the dyed skins with a composition containing tannic acid-bearing materials, striking the skins with an iron compound, applying an alkaline salt in an amount to produce a condition where some iron hydroxide is nearly precipitated, again dyeing the skins to produce the tinctorial efiect desired in the final product, adding an aromatic amine in an amount in excess of that required to precipitate the iron hydroxide, permitting the excess amine to oxidize, drying the skins, and finally subjecting the skins to a finishing treatment.

12. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise treating a plurality of wet back skins containing chrome tannage with an aqueous mineral oil emulsion, dyeing the skins in a dye bath containing a dyestufi requiring a mordant and in the presence of a mordant, adding to the dye bath an organic acid having a dissociation constant not over and in anamount in excess of that required to exhaust the dye whereby an acid environment is produced in the skins, treating the dyed skins with a composition containing tannic acid-bearing materials, striking the skins with an iron salt, neutralizing the acid with an alkaline compound to a point where some iron hydroxide is nearly precipitated, adding an aromatic amine in an amount in excess of that required to precipitate the iron hydroxide, permitting the excess amine to oxidize, drying the skins, and finally subjecting the skins to a finishing treatment.

13. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise treating a plurality of wet back skins containing chrome tannage with an aqueous mineral oil emulsion, dyeing the skins in a dye bath with a dyestuii" requiring a mordant and in the presence of a bichromate polybasic acid mordant, adding to the dye bath an organic acid having a dissociation constant not over 10*, adding an additional dyestufi to the dye bath, again adding said organic acid, the total quantity of organic acid added being in excess of that required to exhaust the dye whereby an acid environment is produced in the skins, treating the dyed skins with a composition containing tannie acid-bearing materials, striking the skins with an iron salt, neutralizing the acid with an alkaline compound to a point where some iron hydroxide is nearly precipitated, adding an aromatic amine in an amount in excess of that required to precipitate the iron hydroxide, permitting the excess amine to oxidize, drying the skins, and finally subjecting the skins to a finishing treatment.

14. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise treating a plurality of wet back skins containing chrome tannage with an aqueous mineral oil emulsion, dyeing the skins in a dye bath containing a dyestufi requiring a mordant and in the presence of a bichromate polybasic acid mordant, intermittently adding to the dye bath at predetermined intervals an organic acid having a dissociation constant not over 10- adding an additional dyestufi to the dye bath, again intermittently adding said organic acid at predetermined intervals, the total quantity of organic acid added being in excess of that required to exhaust the dye whereby an acid enviromnent is produced in the skins, treating the dyed skins with a composition containing tannic acid-bearing materials, striking the skins with an iron salt, neutralizing the acid with an alkaline compound to a point where some iron hydroxide is nearly precipitated, adding an aromatic amine in an amount in excess of that.

the dye bath at predetermined intervals an organic acid having a dissociation constant not over 10- adding an additional dyestuif to the dye bath, again intermittently adding said orgahic acid at predetermined intervals, the total quantity of organic acid added being in excess of that required to exhaust the dye whereby an acid environment is produced in the skins, treating the dyed skins with a composition containing 'tannic acid-bearing materials, striking the skins with an iron salt, neutralizing the acid with an alkaline compound to a point where some iron hydroxide is nearly precipitated, dyeing the skins to produce the tinctorial effect desiredin the final product, adding an aromatic amine in an amount in excess of that required to precipitate the iron hydroxide. permitting the excess amine to oxidize, drying the skins, and finally subjecting the skins to a finishing treatment.

16. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise dyeing a plurality of the selected skins in a drum, separating the fibers by chemically producing a bulky deposit on and between the fibers on the surface of the dyed skins while in said drum, and thereafter removing the skins from the drum and subjecting them to a finishing treatment.

17. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise dyeing a plurality of the selected skins, forming iron hydroxide in and on at least the top portions of the fibers on the surface of the dyed skins by causing an iron compound in the presence of alkaline compounds to react with an aromatic amine, each of the previous steps being performed in a drum whereby a drumming action is secured, and after removing the skins from said drum subjecting the skins to a finishing treatment.

18. In a method of producing a colored suede finish on skins containing chrome tannage, the

, steps which comprise dyeing a plurality of the selected skins in the presence of an amount of weakly ionized organic acid in excess of that re-- quired to exhaust the dye whereby an acid environment is produced in the skins, forming iron tannate in and on at least the top portions of the surface fibers, neutralizing the acid to a point where a portion of the iron hydroxide is nearly precipitated as iron hydroxide, applying an arcmatic amine in excess of that required to precipitate the iron hydroxide, each of the previous steps being performed in a drum with a drumming action, removing the skins from the drum, permitting the excess amine to oxidize, and finally subjecting the skins to a finishing treatment.

19. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise wetting back a plurality of skins containing chrome tann'age for 30 minutes in plain water at from F. to 160 F. in a rotating drum, dropping the liquor, adding a sufiicient quantity of an aqueous mineral oil emulsion to provide approximately 0.25% to 10% of mineral oil, drumming the skins and mineral oil emulsion for 30 minutes at 140 F. to 160 F., dropping the liquor, adding the selected dyestufi, ncorporating a sufficient quantity of a bichromate polybasic acid mordant to act on the dyestufi' employed in the process, drumming the skins and dyestuffs for approximately 45 minutes at 140 F. to 160 F., adding formic acid in three feedings at 10 minute intervals at F., each feeding containing 0.5% to 20% formic acid, adding an additional dyestufl, drumming for 30 minutes at F. to 160 F., adding formic acid in three feedings at 10 minute intervals at 135 F., each feeding containing 0.25% to 20% formic acid, dropping the liquor, adding 1% to 20% of tannic acid-bearing materials, drumming the mass for 30 minutes at F., striking with 0.25% to 20% of an iron salt, drumming for 15 minutes, dropping the liquor, bringing back the temperature to 135 F., adding 0.5% to 10% of an alkaline compound, drumming for 15 minutes, adding 0.625% to 20% ofan aromatic amine, drumming for 1 hour, removing the skins from the drum, horsing up said skins to permit the amine to oxidize, drying said skins in a cool room, and finally subjecting the skins to a finishing operation.

20. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise wetting back a plurality of skins containing chrome tannage for 30 minutes in plain water at from 100 F. to F. in a rotating drum, dropping the liquor, adding a sufficient quantity of an aqueous mineral oil emulsion to provide approximately 0.25% to 10% of mineral oil, drumming the skins and mineral oil emulsion for 30 minutes at 140 F. to 160 F., dropping the liquor, adding the selected dyestufi', incorporating a sufficient quantity of a bichromate polybasic acid mordant to act on the dyestuff employed in the process, drumming the skins and dyestuffs for approin'mately 45 minutes at 140 F. to 160 F., adding formic acid in three feedings at 10 minute intervals at 135 F., each feeding. containing 0.5% to 20% formic acid, adding an additional dyestuif, drumming for'30 minutes at 140 F. to 160 F., adding formic acid in three feedings at 10 minute intervals at 135 F., each feeding containing 0.25% to 25% formic acid, droppingthe liquor, adding 1% to 20% of tannic acid-bearing materials, drumming the mass for 30 minutes at 145 F., striking with 0.25% to 20% of an iron salt, drumming for 15 minutes, dropping the liquor, bringing back the temperature to 135 F'., adding 0.5% to 10% of an alkaline co'mpound, drumming for 15 minutes,

adding. 1% to 10% of a basic aniline dyestufi',

drumming for 30 minutes, dopping the liquor, adding 0.625% to 20% of an aromatic amine, drumming for l'hour, removing the skins from the drum, horsing up said skins to permitthe amine to oxidize, drying said skins in a cool room, and 'finally subjecting the skins to a finishing operation.

21. In a method of producing a colored suede finish on skins containing chrome tannage. the steps which comprise wetting back a plurality of skins containing chrome tannage for 30 minutes in plain water at 160 F. in a rotating drum, dropping theliquor, adding a sufficient quantity of an aqueous mineral oil emulsion to provide approximately 3% of mineral oil, drumming the skins and mineral oil emulsion for 30 minutes, dropping the liquor" and then adding a selected dyestufi, incorporating 3% of a bichromate polybasic acid mordant in the dye bath, drumming the skins and dye bath for approximately 45 minutes at 160 F.. adding formic acid in three feedings at 10 minute intervals at 135 F., each feeding containing 1.25% of formic acid, adding an additional dyestuff, drumming for 30 minutes I a mixture of tannic acid-bearing materials containing 5% of hematlne crystals, 1.5% of fustic crystals and 1.5% of stainless sumac extractat 145 F., drumming the mass for 30 minutes at 145 F., striking with of copperas and 1% of iron nitrate, drumming for 15 minutes, dropping the liquor, bringing back the temperature to 135 F., adding 2% of borax, drummingfor 15 minutes, adding 4% of a basic aniline dyestufi, drumming for 30 minutes, dropping the liquor, adding 1% of paraphenyl diamine, drumming for 1 hour, removing the skins from the drum, horsing up said skins for oxidation, drying said skins in a cool room, and finally subjecting the skins to a. finishing treatment.

22. In a method of producing a colored suede finish on skins containing chrome tannage as setv forth in claim 7, a finishing treatment which comprises covering the previously prepared and dried skins with wet saw-dust, removing the sawdust, staking the skins, blocking the staked skins with an emery block, plushing the skins, ironing, and again staking and'plushing the skins.

23. In a method of producing a colored suede finish on sheep skins as set forth in claim 7, the finishing treatment which comprises covering the previously prepared skins with wet saw-dust for -4 to 12 hours, removing the skins from the sawdustustaking said skins, blocking said skins with an emery block, plushing said skins from the backbone out by a plushing reel rotating at from 1600 to 2500 R. P. M., thereafter ironing said skimns, and then again stakingand plushing said s 24. In amethod of producing a colored suede finish on kid or calf skins as set forth in claim 7, the finishing treatment which comprises covering the previously prepared skins with wet sawdust, removing the skins from the saw-dust, staking said skins, blocking said skins with an emery block, plushing said skins from the backbone,out by a plushing reel rotating at from 1600 to 2500 R. P. M., dry milling said skins in a drum for 6 to 12 hours, and thereafter successively subjecting the skins to toggling, staking, plushing. ironing, staking and plushing operations.

25. In a method of producing a colored suede finish on skins containing chrome tannage, the

- pound in the presence of alkaline compounds to react with an aromatic amine, the quantity of amine being in excess of the amount necessary to produce said iron hydroxide, causing the excess amine to oxidize on the fibers, and subjecting the skins to a finishing treatment.

26. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise treating a plurality of wet back skins with an aqueous mineral oil emulsion, dyeing said skins, forming iron hydroxide in and on at least the top portions of the fibers on the surface of the dyed skins by causing an iron compound in the presence of alkaline compounds to react with an aromatic amine, the quantity of amine being in excess of the amount necessary to produce said iron hydroxide, causing the excess amine to oxidize on the fibers, and subjecting the skins to a finishing treatment.

27. In a method of producing a colored suede .finish on skins containing chrome tannage, the

steps which comprise treating a plurality of wet back skins with an aqueous mineral oil emulsion, dyeing said skins, forming iron hydroxide in and on at least the top portions of the fibers on the surface of the dyed skins by causing an iron compound in the presence of alkaline compounds to reactwith an aromatic amine, each of the previous steps being performed in a drum whereby a drumming action is secured, removing the skins from said drum, and subjecting said skins to a finishing treatment.

28. In a method of producing a colored suede finish on skins containing chrome tannage, .the steps which comprise treating a plurality of wet back skins containing chrome tannage with an aqueous mineral oil emulsion, dyeing the skins in the presence of an amount of a weakly ionized organic acid in excess of that required to exhaust the dye whereby an acid environment is produced in the skins, treating the dyed skins with a composition containing tannic acid-bearing materials, striking the skins with an iron salt, neutralizing the acid to a point where some iron hydroxide is nearly precipitated, adding an aromatic amine in an amount in excess of that required to precipitate the iron hydroxide, permitting the excess amine to oxidize, each of the previous steps being performed in a drum whereby a drumming action is secured, removing the skins from said drum, drying said skins, and

finally subjecting the skins to a finishing treatment.

29. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise dyeing a plurality of the selected skins, separating the fibers by chemically producing a bulky deposit on and between the fibers on the surface of the dyed skins, each of the steps being performed at a temperature of from 100 F. to 160 F. in a drum whereby a drumming action is secured, removing the skins from the drum, and subjecting the skins to a finishing treatment.

30. In a'method of producing a colored suede finish on skins containing chrome tannage, the

' steps which comprise dyeing a plurality of the selected 'skins, forming iron hydroxide in and on at least the top portions of the fibers on the surface of thedyed skins by causing an iron compound in the presence of alkaline compounds to react with an aromatic amine, each of the previous steps being performed at a temperature of from 100 F. to 160 F. in a drum whereby a drumming action is secured, removing the skins from said drum, and subjecting said skins to a finishing treatment.

31. In a method of producing a colored suede finish on skins containing chrome tannage, the steps which comprise treating a plurality of wet back skins with an aqueous mineraloil emulsion, dyeing said skins, forming iron hydroxide in and on at least the top portions of the fibers on the surface of the dyed skins by causing an iron compound in the presence of alkaline compounds to react with an aromatic amine, each of the preceding steps being performed at a temperature of from 100 F. to 160 F. in a drum whereby a drumming action is secured, removing the skins from the drum, and subjecting the skins to a finishing treatment.

ERNEST RUDOLF STERN.

V CERTIFICATE OF CORRECTION. Patent No. 2,201;.,2 62. June 11, 191w. ERNEST RUDOLF STERN.

It is hereby certified that error appears'in the printed specification of the above numbered patent requiring correction as follows: Page )4, first column, line 56, for "of" read -at--; page 6, first column, line 69, claim 19, for "ncorporating" read "incorporating"; same page, second column, line 58, claim 20, for "025% to 25% read 0.25% to 20%"; line 1 .7', same claim, for "donning" read --dropping--; line 72, claim 21, for "minutes" read -min mizeand that the said Letters Patent should be read with this correction therein that the same" may conform to the record of the case i the Patent Office. I

Signed and sealed this 50th day of July, A. 1). 191m.

Henry Arsdale,

(Seal) Acting Commissioner of Patents. 

